I bought the B version, it looks the best for me. It really is a quality product. The only downside is, it raises your front sight and you have to aim differently to shoot in the right direction (vertically). Or you have to change your rear too. Otherwise, it has every screw hole that the original has and they are in the right position so your factory underrail will fit on this. Easy to change from the factory barrel, but you might not be able to use the factory inner barrel's positioning rubber (too narrow place for it) with this one.